1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine having plural functions thereof.
2. Description of the Related Art
An image forming apparatus of an electrophotographic system has been widely known in the related art. In addition to a monochrome type, a variety of image forming apparatuses which perform full-color image forming have been introduced to the market. Here, in accordance with extending of various usage areas of the image forming apparatuses, the need for improved image quality have been growing.
Adding varied gloss expression has been desired as one of factors to improve the image quality. Specifically, it is desired to mix a low glossiness part and a high glossiness part on a surface of an output product. For example, an image of character information (i.e., a document area) is finished in low glossiness for easy reading. On the other hand, a gradation image, such as a picture or an illustration (i.e., a graphics area), is finished in high glossiness for enhanced appearance. In addition, emphasized expression is performed by forming a high glossiness part partially in a gradation image.
In US2007/280759, glossiness of an image is adjusted by separately providing a clear image forming portion which forms a clear toner image in a conveying direction downstream from a recording material of a color image forming portion which forms a color toner image. Here, the color toner image is heated at both the color image forming portion and the clear image forming portion. On the other hand, the clear toner image is heated only at the clear image forming portion. Therefore, it is difficult to increase the glossiness of the area where the clear toner image is formed so as to be higher than that of the area where the clear toner image is not formed.